Polylactic acid block copolymers and preparation methods thereof

a technology of polylactic acid block and copolymer, applied in the field of polylactic acid, can solve the problems of limited wide application range, poor crystallization ability of pla, and high brittleness of pla, and achieve the effect of high melting poin

Active Publication Date: 2016-06-14
NINGBO INST OF MATERIALS TECH & ENG CHINESE ACADEMY OF SCI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0040]Compared with the irregular aromatic polyester-polylactic acid copolymer obtained by melt phase polycondensation, the aromatic polyester-polylactic block copolymer prepared according to the present invention has explicit structure. Moreover, the reaction conditions of the present invention are moderate, thus reducing the racemization and degradation between the raw material lactide and the product polylactic acid seldom happen. Besides, the present invention can be used to study the effects of different block structure and the content thereof on the crystallization property as well as thermal properties of another block, and can be used as compatilizer to study the effects on the compatibility and the mechanical performance of the relevant blend of aromatic polyester and aliphatic polyester. The present invention adopts the stepwise polymerization method, comprising firstly initiating the polymerization of cyclic aromatic polyester oligomer, and then initiating the ring-opening polymerization of lactide in order to obtain the polylactic acid block copolymer. Compared with anionic polymerization, the synthesis according to the invention is easy and the operation is simple.
[0072]According to the present invention, the solution polymerization method is used, wherein the organic solvent that can dissolve the reactants dihydroxyl terminated aromatic polyester and lactide is used as reaction medium, the tin salt is used as catalyst, and the dihydroxyl terminated aromatic polyester is used as an initiator for initiating the ring-opening polymerization of lactide in the solvent, thus effectively introducing polylactic acid block into aromatic polyester, and obtaining polylactic block copolymer. Not only the block copolymer containing polylactic acid block with single configuration, but also the block copolymer containing poly lactic acid block with two or three types of configuration can be obtained.
[0110]The present invention use the solution polymerization method, wherein the dihydroxyl terminated aromatic polyester and lactide are dissolved in a certain amount of organic solvent, and then the catalyst is added. The dihydroxyl terminated aromatic polyester is used as an initiator to initiate the ring-opening polymerization of lactide, thus obtaining block copolymer of aromatic polyester and polylactic acid. The reaction conditions of this method are mild, therefore, the polymerization temperature cam be controlled within the range in which the polylactic acid and lactide won't degrade, even won't racemize, so as to prevent transesterification from occurring and ensure the regularity of the segment, thus obtaining block copolymer of polyester and polylactic acid including aromatic polyester of high melting-point. Moreover, the block copolymer with polylactic acid of single configuration, the block copolymer with polylactic acid of two types of configuration or the block copolymer with poly lactic acid of three types of configuration can be prepared by the method according to the present invention, thereby obtaining the block copolymer of aromatic polyester and polylactic acid of explicit sequential structure.

Problems solved by technology

PLA has a broad range of application and enormous market potential, however, compared with the aromatic polyesters such as PET, PLA possesses higher brittleness and poor impact resistance, which has limited its wider applications.
As a result, PLA possesses poor crystallizability, even no crystallizability.
Then, the coupling reaction was carried out in the molten state at 140-210° C. However, since this reaction was performed by coupling method in the molten state, the product is the mixture of polymers with complex structures and is difficult to separate, it's impossible to obtain block copolymer with the definite structure.
Therefore, it is not feasible to synthesize the block copolymers of PLA and polyesters with higher melting temperature by melt-polycondensation.

Method used

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  • Polylactic acid block copolymers and preparation methods thereof
  • Polylactic acid block copolymers and preparation methods thereof
  • Polylactic acid block copolymers and preparation methods thereof

Examples

Experimental program
Comparison scheme
Effect test

example 1

[0112]Step 1: The ring-opening polymerization of cyclic poly butylene terephthalate (CBT), that is, the preparation of the macrocyclic poly butylene terephthalate (PBT).

[0113]Under N2, the CBT (10 g) and stannoxane catalyst (0.5 g) were loaded into a flask (100 mL) which was baked, protected under N2 and cooled. The dehydrated and de-oxygened o-dichlorobenzene was added into the flask by a syringe and the concentration of monomer CBT was 2 kg / L. The reaction was carried out at 180° C. and monitored by GPC. After 10 minutes, the signal peak of CBT disappeared and the reaction was quenched. The obtained product was cooled and filtered, and washed with dried CHCl3 to wash away the residual monomer CBT. The product was dried at 60° C., and the PBT containing catalyst was obtained.

[0114]Step 2: The polymerization of lactide initiated by the PBT containing catalyst.

[0115]Under N2, the PBT (0.5 g) prepared in step 1 and L-lactide (5.0 g) were added into a dried and de-oxygened flask (100 m...

example 2

[0123]Step 1: The ring-opening polymerization of cyclic poly ethylene terephthalate (CET), which was the preparation of the macrocyclic poly ethylene terephthalate (PET).

[0124]Under N2, the CET (10 g) and stannoxane catalyst (0.05 g) were loaded into a flask (100 mL) which was baked, protected under N2 and cooled. The dehydrated and de-oxygened solvent chlorobenzene was charged into the flask by a syringe and the concentration of monomer CET was 1 kg / L. The reaction was carried out at 120° C. and was monitored by GPC. After 48 h, the signal of CET disappeared, and then the reaction was quenched. The system was cooled to room temperature. After that, the product was filtered and washed with dried CHCl3, and the residual monomer CET was washed away. The product was vacuum dried at 60° C., and the PET containing catalyst was obtained.

[0125]Step 2: The polymerization of lactide which was initiated by the PET containing catalyst.

[0126]Under N2, the PET (0.5 g) obtained in step 1 and D-la...

example 3

[0129]Step 1: the ring-opening polymerization of cyclic poly butylene isophathlate, which was the preparation of the macrocyclic polybutylene isophathlate.

[0130]Under N2, the cyclic poly butylene isophathlate (10 g) and stannoxane catalyst (0.1 g) were loaded into a flask (50 mL) which was baked, protected under N2 and cooled. The mixed solvent of o-dichlorobenzene and chlorobenzene of which V:V=2:1 was charged into the flask by a syringe and the concentration of monomer cyclic poly butylene isophathlate was 2 kg / L. The reaction was carried out at 180° C. and was monitored by GPC. After 10 minutes, the signal of cyclic butylene isophathlate disappeared, and then the reaction was quenched. The system was cooled to room temperature. After that, the product was filtered and washed with dried CHCl3, and the un-reacted monomer was washed away. The product was vacuum dried at 60° C., and the polybutylene isophathlate containing catalyst was obtained.

[0131]Step 2: the polymerization of lac...

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Abstract

A polylactic acid triblock copolymer and a preparation method thereof are described. The polylactic acid triblock copolymer comprises an aromatic polyester oligomer block and a polylactic acid block. The polylactic acid triblock copolymer is obtained by reacting an aromatic polyester oligomer with a monomer lactide at a desired temperature. The polylactic acid block copolymer has a regular structure indicated by peak melting temperatures (Tm) corresponding to the aromatic polyester oligomer block and the polylactic acid block, respectively. Examples of the aromatic polyester oligomer block include polyethylene terephthalate, polybutylene terephthalate, and polyethylene 1,4-naphthalate. Examples of the monomer lactide include L-lactide and D-lactide.

Description

[0001]This application claims priority to Chinese Application No. 201010568888.0 filed on Nov. 30, 2010, the title of which is “Aromatic-aliphatic block copolyester and preparation method thereof”, and Chinese Application No. 201110122513.6 filed on May 12, 2011, the title of which is “Polylactic Acid block copolymer and preparation method thereof”, and the disclosure of two of the applications is incorporated herein by reference in its entirety.FIELD OF INVENTION[0002]the present invention relates to the field of polylactic acid, particularly to a polylactic acid block copolymer and the preparation method thereof.BACKGROUND OF INVENTION[0003]People are interested in poly lactic acid (PLA) since the raw material thereof, lactic acid is derived from biological source and can be biodegraded, and PLA has the similar process ability and mechanical properties as common plastics such as PP and PE. PLA has a broad range of application and enormous market potential, however, compared with t...

Claims

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Application Information

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Patent Type & Authority Patents(United States)
IPC IPC(8): C08G63/08C08G63/60
CPCC08G63/08C08G63/60
Inventor ZHOU, JIANCHEN, PENGGU, QUNLI, JUNSHI, WENTAOWANG, ZONGBAOJIANG, ZHIQIANGWU, XUEDONG
Owner NINGBO INST OF MATERIALS TECH & ENG CHINESE ACADEMY OF SCI
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